In recent years, it has been discovered that products having fine concave-convex structures with a period that is not more than the wavelength of visible light on the surface of the product exhibit an anti-reflective effect and a lotus effect and the like. In particular, it is known that a concave-convex structure known as a moth-eye structure, which contains an array of substantially conical convex protrusions, acts as an effective anti-reflective device by continuously increasing the refractive index from the refractive index of air to the refractive index of the material of the product.
In terms of the method used for forming a fine concave-convex structure on the surface of a product, a method in which a liquid active energy ray-curable resin composition is used to fill the space between a mold having a fine concave-convex structure on the surface and a substrate, and the resin composition is then cured by irradiation with active energy rays, thereby forming a cured resin layer into which the fine concave-convex structure has been transferred on the surface of the substrate, is attracting much attention.
Further, as the aforementioned mold, a mold composed of an anodized alumina having two or more fine pores on the surface of an aluminum substrate is garnering much attention due to its ease of production (Patent Document 1).
However, in the aforementioned mold, because the period of the fine pores is at the nanometer level, and the aspect ratio of the pores is also comparatively large, the contact interface between the mold and the active energy ray-curable resin composition increases significantly. As a result, a problem arises in that the mold is difficult to release from the cured resin layer.
The following methods have been proposed as methods of improving the releasability between the mold and the cured resin layer.
(1) A method in which the surface of the mold on which the fine concave-convex structure is formed is treated with a release agent (external release agent) (Patent Document 2).
(2) A method in which instead of using a liquid photocurable resin composition, a solid photocurable transfer layer is used which is composed of a photocurable resin composition containing a phosphate ester-based compound as a lubricant (internal release agent) (Patent Document 3).
However, in the method (1), when the fine concave-convex structure of the mold is repeatedly transferred, the release agent is gradually stripped from the surface of the mold, and the releasability gradually deteriorates. When the releasability deteriorates, productivity of the product decreases, and portions of either the fine concave-convex being transferred or the product can become damaged, meaning the transfer precision also deteriorates.
In the method (2), in the case of particularly fine and deep concave-convex structures, or depending on the material used for the mold, satisfactory releasability may not be obtainable. Further, because the fluidity of the photocurable transfer layer is low, when the mold is pressed against the photocurable transfer layer, heating arid/or a large amount of pressure are required, which not only places a considerable load on the mold and the apparatus, but in the case of particularly fine and deep concave-convex structures, makes it difficult to achieve satisfactory transfer precision. Furthermore, the takt time also increases, and the productivity is low.